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Genetic counseling: Bloom Syndrome-2
Bloom Syndrome (Also known as Bloom-Torre-Mackacek syndrome, BS, Levi's Type Dwarfism, Short Stature and Facial Telangiectasis) Introduction *Acknowledge any prior contact with patient *Assess concerns and questions of the patient and his/her family *Assess knowledge of this condition and why the patient thinks he or she was referred to genetics *Patient's Medical History *Family Medical History and Pedigree Genetic Etiology *Mode of Inheritance: Autosomal recessive *Chromosome Location: BLM gene mutation at locus 15q26.1 *Molecular Genetics: A cytogenetic diagnosis is made via increased rate of chromosome breakage and sister chromatid exchange Incidence and Carrier Frequency *Since this is an inherited disorder, an affected parent has a 25% chance of passing on this syndrome to a child. Fifty percent of an affected parent's children will be carriers for this disease (carriers are usually asymptomatic). *Bloom syndrome is an incredibly rare disorder, with approximately 140 cases having been reported. It affects males slightly more than females. It is more prevalent in the Ashkenazi Jewish population, with an estimated carrier rate of 1 in 104. Clinical Features *Short stature with normal body proportions *Multiple small, dilated blood vessels on the face (facial telangiectasia) and on other light-exposed areas *Photosensitivity *Susceptibility to infections due to immune system defect *IUGR *Abnormally high-pitched voice *Dental anomalies *Prominent ears *Cysts at the base of the spine *Polydactyly *Acanthosis nigricans on parts of the body other than the face Natural History *As life progresses, patients with Bloom syndrome have an increased rate of malignant tumors, especially leukemia and squamous cell cancer of the skin. Diarrhea and vomiting are also common. Frequent infections and problems associated with short stature are also present. *Life expectancy is variable. Death is often a result of cancer. *Preterm labor has been shown to occur in women with Bloom syndrome. They also have a shorter reproductive span and reduced fertility. Men with Bloom syndrome are sterile. Testing *Chromosome analysis is typically done to detect Bloom syndrome. Most often, chromosome fragility testing is performed to make a cytogenetic diagnosis. Treatment *Affected individuals should use sunscreen and should avoid direct contact with sunlight. Patients should have regular evaluations by dermatology, general medicine, genetics, and oncology. If an infection occurs, it should be treated aggressively with antibiotics. *Research on therapies is ongoing. *Psychosocial Issues *Affected patients and their family members may react initially to diagnosis with shock, frustration, denial, anger, fear, sadness, depression, guilt, and loss. The fact that patients with this syndrome require constant medical follow-up may be overwhelming for patients and families. Affected patients may have low self-esteem due to facial erythemia and their photosensitivity may make individuals (especially children) resentful of their condition, since it limits outdoor activities. Reproductive issues should also be considered with a genetic counselor, depending on the age of the patient when diagnosis is made. Support Groups *Bloom's Syndrome Registry :NY Blood Center :310 East 67th Street :New York, NY 10021 :Telephone 212-570-3075 *National Foundation for Jewish Genetic Diseases :250 Park Avenue :Suite 1000 :New York, NY 10017 :Telephone 212-371-1030 *MAGIC Foundation for Children's Growth :1327 North Harlem Avenue :Oak Park, IL 60302 :Telephone 1-800-362-4423 :www.magicfoundation.org References *Mendelian Inheritance in Man, POSSUM database, NORD database, GeneTests website Notes The information in this outline was last updated in 2002. Material obtained under GFDL Licence from http://en.wikibooks.org/wiki/Handbook_of_Genetic_Counseling